Foucault Gyroscope showing Earth Rotation, version 2 

Ha ha! Welcome to the world of precision measurements with amateur equipment. I went down the floating route too. The main problem I ran into there is that water has a surprising amount of viscosity and surface tension in comparison to the force we're trying to measure. (Hint: Make sure the water is clean. Viscosity builds quickly as it gets colonized by microorganisms.) The gyrocompass I built was an accidental discovery while tinkering with what was intended to eventually be a full float-based gyroscope. I agree it's a wonder Foucault did it. If he had a competent machinist (which I am not!) working with him, someone who could make a really good, properly balanced, bearing, I think it's possible. Also, my understanding is he used a significantly bigger flywheel, maybe 8cm diameter? More rotational inertia could be a major help.

Thank you! I haven't made more videos on this topic because I think the videos I've already made have sufficiently answered the questions "does the Earth rotate?" (yes: See gyrocompass video, link in description) and "is the Earth a sphere?" (yes: See "measuring the earth with the stars" video). Crucially, these have been answered in a way that anyone with a few hundred dollars can replicate themselves. I'm not interested in riding the meme, I only care about the science.

Thanks! You're right, this is difficult, much more so than I imagined when I originally started working on it. I regard this experiment as only a partial success; I'm confident it was measuring Earth rotation for a few minutes at a time, but it's not persuasive to a skeptic, among other reasons because of the difficulty of replication. The gyrocompass on the other hand (see link in the description) is, in my opinion, fully successful and ought to be persuasive to an open-minded skeptic.

​@@GarbageGamer74You're not going to find open-minded skeptics among the Flat Earthers. Nobody else needs persuasion, the movement of the stars and solar system are enough to prove rotation of the Earth to any sensible person. Still it's a fun and challenging experiment and worth the experience gained in attempting it I think.

I don't understand the Schuler pendulum suggestion. My apparatus is sitting on a motionless table, then in fairly still water. What unwanted motion is there to cancel? I've read about air powered gyros, but I don't understand how to build one that would avoid the problem of the air causing a torque. Even my electrically powered gyro generates enough air current coming off the (seemingly smooth) flywheel to create measurable torque if I don't have the paper cowling on it.

GarbageGamer74 The schuler will keep small perturbations from you mount moving out of your experiment. You want only the gyro axis to be marked by the laser pointer. But I think a Schuler pendulum would require quite a large mounting system to be effective. I think you could do away with the floating apparatus.., Just blue skying. I haven't considered such an apparatus as your before.

I see. I haven't seen anything to suggest I need more isolation from the environment, other than the Earth's magnetic field. Is there some extraneous motion you see in the video that you think the pendulum would eliminate? The floating bearing seems to work very well for the yaw axis, so I see no need to replace that part. The pitch axis is the part that doesn't work as well as I would like.

GarbageGamer74 Nothing specific. I only suggest it as a potential to damp more/any extraneous motion in your gimbal setup. I know an electronic version of Schuler's is used in aircraft gyroscopes to damp out the long period oscillation caused by the gyroscope travelling across the earths surface.., Might not be too applicable to your benchtop.

The main problem is the "freely rotating on gimbals" part. This video shows my best attempt at balanced gimbals with sufficiently low friction, and it's only good enough to track Earth rotation for a few minutes at a time. If you want direct physical evidence that the Earth rotates, check out my gyrocompass videos.

GarbageGamer74 I know what you mean, but what I'm suggesting is to put the ball in the flat earthers' court as far as friction is concerned. The rotating cage would already be 'steady in space' and not have to deal with friction to maintain its orientation.

Oh, I understand now. Indeed, placing the gimbals on or inside something that slowly rotates would effectively test whether the friction is too high. From my experience, when using this particular flywheel, I can report that if, when you breathe near the gimbals, they don't turn, the friction is too high. If the motor's magnet does not act like a magnetic compass, the friction is too high. If resting a few centimeters of fine thread on one side does not upset the balance, the friction is too high. Even at max speed, the angular momentum of this flywheel is very small, so it requires a very sensitive instrument to use it to detect Earth's rotation.

The magnetic field could be blocked with mu-metal foil, but at around $1 per square inch it's not super cheap. Another approach is to build a Helmholtz coil, like these guys did: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-zkYWRgQmBKE.html . Yet another approach, which I've been tinkering with, is to add small permanent magnets to the boat that mostly cancel the torque of the magnet in the motor. I do need the motor; I already tried without it. Foucault's flywheel was much larger, so had far higher angular momentum, but the small flywheel in this gyro has low angular inertia and also spins down very quickly, losing most of its angular momentum in a minute or so, and coming to a complete stop in around 10 minutes. Also, as it spins down due to bearing friction, it transfers angular momentum to the boat, causing a torque, because I can't mount it perfectly vertically. I don't know how Foucault solved that problem. Air doesn't cause precession per se, but it does cause a torque, sort of like a spinning propeller. My setup would rotate slowly due to that before I added the cowling. It is also requires still air in the vicinity of the device, since any ambient air currents will be detected.

Yes, I think so, as explained around 12:50. I am unaware of any other plausible explanation for the observed motion highlighted with the blue lines. But I can understand not being convinced by the result of this experiment. Please see my gyrocompass video (link in the description) for, IMO, a much more compelling direct demonstration of the Earth's rotation.

No. There is no rotation. This experiment is flawed in many ways.

Thanks! :)

The gyroscope must spin and tilt freely.

I've considered doing this before, by putting the gyro on a turntable (like a record player). This would test whether the gimbals have too much friction to measure rotation as slow as the Earth. However, I consider the gyrocompass experiment (see link in description) to be a better demonstration, so haven't felt the need to further refine the experiment shown in this video.

I agree the experiment could be more convincing. You might want to check out my gyrocompass video (link in description), which I think is more convincing, and is much easier for someone else to replicate.

Yes, an ideal gyro's flywheel's spin axis will maintain a constant direction in 3D space. Distant stars merely provide a useful way to identify such directions; of course the gyro does not know they are there. In what way have I misstated the apparent motion of stars from Earth?

Then why are there different star trails depending on where you are? And why are there different stars that rotate around the poles?

Allen Stanler It has been explained, models have even been made. Google: flat earth stars explained. The Star trails actually disprove the standard globe model if you would just use basic critical thinking skills about the pattern we see. A better question is: why are we unable to detect any curvature or rotation?

Nicholas Pitts I actually watched that video already, it’s just a big straw man that doesn’t match up with observable reality, and the model hasn’t been proven either. “Perspective” also isn’t a good excuse. Also, we are able to detect movement, leave a Gyroscope spinning long enough and it visibly moves with the earths rotation. This has been observed hundreds of years ago. Also, the Sagnac Effect wouldn’t work a flat earth either, as the devices used inside that detect rotation wouldn’t function. Also, the Coriolis effect is a big offender to the flat earth model.

Allen Stanler it does match.. Thad the point of the model to show that it could work.. god forbid we try to explain what we see. What gyro can detect earth’s rotation?? This is big news please link us to the experiment. There is no coriolis. When will you realize you can’t have it both ways? If you want to believe things you will eventually need proof.

Nicholas Pitts No, it doesn’t work, the display of the stars would have a visible curve to them, and would be able to approached. That, and it isn’t proven, it’s a very elementary hypothesis. Also, you put a gyroscope in a frictionless mounting, you can observe it’s rotation. There is no specific gyroscope you seem to be clamoring about. Also, no Coriolis? Guess you can explain to me why the Jet Stream doesn’t exist too.

How do you know?

Scott McPeak Gaming no test has ever been able to detect motion throughout history. Every time one was done no motion was detected and major scientific theories needed to be rejiggered, it got to be very expensive, they no longer can handle their fallacies it costs too much, they only ignore them. There is no Coriolis there is no motion if you think motion exists provide the experiment.

observations of the Jovian moon eclipses show that the earth is in orbit around the sun at 93 million miles, the times drift out by 18 minutes which is the length of time it takes light to traverse the diameter of the orbit. This actually confirmed the speed of light Isn't science great

spookdad Wrong. If you are speaking of the Jovian shadow of the moon on the earth that has actually recently disproven the estimated size of the moon. As far as eclipses in general there are multiple theories for what causes the shadow.. or even why a flat earth would produce a curved shadow.. either way it’s not empirical evidence of curvature.

eh? you have not understood, plus there is no way any of the Jovian moons would cast a shadow on the earth that is just preposterous I am describing the eclipses of the Jovian moons behind their host planet Jupiter, it was attempted to use these times to aid navigation however it was discovered that the timings of these eclipses drift out by 18 minutes when the earth is on the opposite side of the sun to Jupiter and then drift back in 18 minutes as we orbit back towards the same side of the sun as Jupiter. These time anomalies were actually used to confirm the speed of light. your original post states "Earth doesn’t move." I have just proven it does so now you change the goal posts and ask for evidence of curvature smh you do realise the earth is really really big? and humans are really really small curvature will not be easily discernible

+aram akdam Yes, the earth rotates. Care to prove it does not? Mind you, yelling with ALL CAPS will not help make your point. You grade school drop-outs are too funny. Pleas go back, try not to flunk thi time.

aram akdam sorry but ALL of the fiber-optic gyroscopes in the world say you are wrong. I test these Gyros as part of my job. They certainly DO measure the Earth's rotation.

If you fly across the Atlantic from Europe to America, you can stay in daylight the whole time. Because planes fly at pretty close to the same speed as the earth's rotation at middle latitudes, the sun stays in the same position in the sky and you land pretty much at the same local time as you originally took off, hours before. I don't expect you to wrap your head around that. I'm just stating it as an interesting fact for the intelligent people in the thread to consider.

@Eduardo Cobian I dont need to, there are many - “100% Proof that Earth Spins! Aircraft Laser Gyroscopes”, or “Understanding the ADIRU | Training | Honeywell”, or “IRS Align Mode - Carefully Measuring Earth's Rotation”

@Eduardo Cobian I am not understanding your comment. I GAVE YOU THREE examples of videos that explain this effect, and THERE ARE MORE. I cannot personally make a video at work.. recording inside my facility is against the rules and requires an approval for release.

In this video, the spin axis points West. The rotation of the Earth causes the axis to move down and right (North), just like a star in the celestial equator (or the Sun), setting in the West. That movement is visible here, although only when the gyro is perfectly balanced. In some other experiments, I had the spin axis pointed East. In that case it ought to move up and right (South), like a star rising, and it does sometimes, but that is similar to the movement caused by precession when the gyro is not balanced, so it is hard to distinguish the two and be sure I'm measuring the Earth.

What published evidence?

Extra J I think he’s referring to the Flat Earthers Laser gyroscope experiment- oh snap, that one proved the earth rotates.